title: Quercetin and its principal metabolites, but not myricetin, oppose lipopolysaccharide-induced hyporesponsiveness of the porcine isolated coronary artery.
abstract: OBJECTIVE
  Quercetin is anti-inflammatory in macrophages by inhibiting lipopolysaccharide (LPS)-mediated increases in cytokine and nitric oxide production but there is little information regarding the corresponding effect on the vasculature. We have examined the effect of quercetin, and its principal human metabolites, on inflammatory changes in the porcine isolated coronary artery.
  
  
  METHODS
  Porcine coronary artery segments were incubated overnight at 37°C in modified Krebs-Henseleit solution with or without 1µg·mL(-1) LPS. Some segments were also co-incubated with quercetin-related flavonoids or Bay 11-7082, an inhibitor of NFκB. Changes in isometric tension of segments to vasoconstrictor and vasodilator agents were recorded. Nitrite content of the incubation solution was estimated using the Griess reaction, while inducible nitric oxide synthase was identified immunohistochemically.
  
  
  RESULTS
  Lipopolysaccharide reduced, by 35-50%, maximal contractions to KCl and U46619, thromboxane A(2) receptor agonist, and impaired endothelium-dependent relaxations to substance P. Nitrite content of the incubation medium increased 3- to 10-fold following exposure to LPS and inducible nitric oxide synthase was detected in the adventitia. Quercetin (0.1-10µM) opposed LPS-induced changes in vascular responses, nitrite production and expression of inducible nitric oxide synthase. Similarly, 10µM Bay 11-7082, 10µM quercetin 3'-sulphate and 10µM quercetin 3-glucuronide prevented LPS-induced changes, while myricetin (10µM) was inactive. Myricetin (10µM) prevented quercetin-induced modulation of LPS-mediated nitrite production.
  
  
  CONCLUSIONS
  Quercetin, quercetin 3'-suphate and quercetin 3-glucuronide, exerted anti-inflammatory effects on the vasculature, possibly through a mechanism involving inhibition of NFκB. Myricetin-induced antagonism of the effect of anti-inflammatory action of quercetin merits further investigation.
authors.affiliation: School of Biomedical Sciences, Faculty of Medicine and Health Sciences, University of Nottingham, Nottingham, UK.
authors.forename: Salmin
authors.initials: S
authors.lastname: Al-Shalmani
authors.forename: Sunita
authors.initials: S
authors.lastname: Suri
authors.forename: David A
authors.initials: DA
authors.lastname: Hughes
authors.forename: Paul A
authors.initials: PA
authors.lastname: Kroon
authors.forename: Paul W
authors.initials: PW
authors.lastname: Needs
authors.forename: Moira A
authors.initials: MA
authors.lastname: Taylor
authors.forename: Sandra
authors.initials: S
authors.lastname: Tribolo
authors.forename: Vincent G
authors.initials: VG
authors.lastname: Wilson
mesh_terms: D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid / Q000494:pharmacology; D000818:Animals; D003331:Coronary Vessels / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D016207:Cytokines / Q000037:antagonists & inhibitors / Q000378:metabolism; D005419:Flavonoids / Q000494:pharmacology; D066298:In Vitro Techniques; D007249:Inflammation / Q000188:drug therapy / Q000378:metabolism / Q000517:prevention & control; D007537:Isometric Contraction / Q000187:drug effects; D008070:Lipopolysaccharides / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000378:metabolism; D009569:Nitric Oxide / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000037:antagonists & inhibitors / Q000378:metabolism; D009570:Nitriles / Q000494:pharmacology; D009573:Nitrites / Q000037:antagonists & inhibitors / Q000378:metabolism; D011189:Potassium Chloride / Q000494:pharmacology; D011794:Quercetin / Q000031:analogs & derivatives* / Q000378:metabolism* / Q000494:pharmacology*; D013450:Sulfones / Q000494:pharmacology; D013552:Swine
chemical_list: C434003:3-(4-methylphenylsulfonyl)-2-propenenitrile; D016207:Cytokines; D005419:Flavonoids; D008070:Lipopolysaccharides; D016328:NF-kappa B; D009570:Nitriles; D009573:Nitrites; D013450:Sulfones; C531389:quercetin 3'-sulfate; C443401:quercetin 3-O-glucuronide; D009569:Nitric Oxide; D011189:Potassium Chloride; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; C040015:myricetin; D011794:Quercetin; D052247:Nitric Oxide Synthase Type II